Question

1) The mean of eight numbers is 75. If the mean of three of the numbers is 60, find the mean of the remaining five numbers

Answer 1

1.
mean=average of all them


(a+b+c+d+e+f+g+h)/8=75
a+b+c+d+e+f+g+h=600


(a+b+c)/3=60
a+b+c=180
subsitute

a+b+c+d+e+f+g+h=600
180+d+e+f+g+h=600
minus 180 both sides
d+e+f+g+h=420
divvide both side by 5
(d+e+f+g+h)/5=84
the mean is 84




2.
1/3 are increased by 6
that means 30 of them are increased by 6
30*6=180
adds 180 to total
180/90=2
increases mean by 2
47+2=49
new mean is 49



c.
v=hpir^2
h=50ft, or 12*50in or 600in
r=1
v=600pi1^2
v=600pi
use 3.14
v=1884 cubic inches